“His plan was to wait until Alexia was around twenty-one, too, and then tell her. But she was always one for sneaking around, snooping and spying. She must have overheard, because it turned out she found the stuff when she was about ten, and started taking it secretly on her own. Probably took far too much. She later said she’d decided she didn’t want to grow any older, because she ‘didn’t like the look of it.’ Funny thing is, Alexia hates children.

“It was a few years later that I left them. I was still a young man, and I stopped taking the brew long before I would have noticed any difference, anyway. For several years, well, things just seemed normal—I mean as far as my body went. There were no effects from the potion I could see. I had assumed that when I stopped taking it, that would be an end to it.

“Turns out I was wrong. Years later, I gradually started to notice I wasn’t growing any older, even though it had been a long time since I took it. Or, at least, if I was aging, it was happening very slowly. Some kind of lingering effect of the potion, you see. It was in my system, replicating in my blood, and, ah, keeping me . . . frozen.

“And, well, that rather complicated life for me. You learn that you, eh, have to disappear from your friends before they start to notice, y’see? Avoid having your photograph taken, that kind of thing. Keep moving. You end up rather alone.

“Harry was the first person I ever told, actually. I had him help me out in a bit of an escapade when he was a boy—there was a chimney and he agreed to climb down the inside, and it all got slightly more . . . supernatural than I’d anticipated. Harry seemed to take it in his stride, though, so I thought I might as well tell him about me.

“But then something marvelous happened. In the years after the Second World War, I noticed I had gradually started aging again, after all. I monitored the situation for a decade or so, to be certain, and it seemed like everything was back to normal. I thought the effects had finally worn off. Or, at least, I allowed myself to pretend that I believed that. And that’s when—well. That’s when I met your grandmother and . . .”

He broke off and cleared his throat. Alex felt his own tightening. The branches of the trees shushed around them.

“Well, that’s a whole other story,” the old man continued. “But, to get back to the point: seems I was wrong again, ha. The potion’s effects returned. I eventually noticed my aging processes had stopped again. But this time something was different.